1. Field of the Invention
The present invention relates generally to an inflatable safety bag system for vehicles which provides inflation of a safety bag so as to protect a driver from harm at the time of a vehicle collision.
2. Description of Relevant Art
An inflatable safety bag system for vehicles detects an impact when a vehicle collides and, if such an impact exceeds a predetermined degree, actuates a gas generator so as to inflate a safety bag, thereby lessening the impact on the driver or other passengers for an improved degree of safety for vehicles. Known safety bag systems comprise a safety bag, a gas generator, actuator means, and impact detecting means.
Because safety bag systems require energization of highpressure gas, they generally employ an electrical squib for electrically detecting an impact to detonate an explosive material such as gunpowder, thereby actuating the gas generator. Such utilization of a squib, however, has presented various problems, such as generation of explosion noise. Also, the squib is susceptible to humidity, making it difficult to detonate and it is thus impossible to confirm with certainty the operability of the system after it is assembled.
Further, a safety bag system as described above has attendant therewith a number of shortcomings with regard to the impact detecting device and actuation device thereof.
Because the actuator means employing the squib has the above-described disadvantages, an actuator means of another type has long been desired. The inflatable safety bag system, and the actuator means in particular, should meeet numerous requirements. For exaple, because the actuator means is dispensed with after it is used only once, it should be inexpensive, should be easily mass-produced, and should have a simple structure. Further, the actuator means must be reliably operated within an extremely short period of time.
A known inflatable safety bag system includes a high-pressure gas generator, or more specifically a high-pressure gas container which releases a gas by the actuator means on detection of an impact to supply gas into a safety bag so as to inflate the bag. The high-pressure gas filling the container may possibly leak therefrom over a period of time, and gas temperature and pressure changes depend on ambient conditions. Accordingly, there has been provided in the gas container a small auxiliary container filled with gas under substantially the same pressure as that of the gas in the main gas container, so as to detect a gas leakage by sensing pressure differences between the main gas container and the auxiliary container. However, with the auxiliary container disposed in the main container, the effective volume in the main container is reduced.
There has been proposed the use of a pressure gauge outside the gas container, instead of the use of an auxiliary container. With such pressure gauge, however, it is difficult to determine the difference between a gas pressure change due to a temperature change and a gas pressure change due to a gas leakage.
With the foregoing shortcomings of known systems being considered, the present invention provides an inflatable safety bag system which eliminates the above-discussed problems and deficiencies associated with known systems, and further provides a system which operates reliably at the time of a vehicle collision.